In the international patent application WO-A-95/03619, a switch of the aforementioned type is proposed for us as a limiter. A large-surface resistor body, with an electrical resistivity that is considerably higher than that of a metal, is used to prevent localized fusing of the electrodes n the case of a short-circuit shutoff due to the plane propagation of the current flow; uniform heating of a gas volume present in the closed housing made of insulated material is also favored by the high-intensity discharges on the resistor material.
Switching with thermoelectric drive, which is the principle of the above-described switch, is therefore based on heating suitable resistor elements, such as disks made of carbon black-filled polyethylene, instantaneously at the contacting boundary surfaces and producing a high-pressure gas blanket through material decomposition that releases mechanical energy through a piston in the case of a short circuit. The thermal and electrical properties of the best resistor materials currently available require that the nominal current be limited to a current density of approximately 1 A/cm.sup.2 at a contact pressure of approximately 100 N/cm.sup.2 for AC3 operation. Electrodes and resistor disks of approximately 18 cm diameter and contact forces of approximately 25 kN would be needed to extend the above-mentioned switching principle to nominal currents of 250 A, for example.
This means that the mechanical design of a thermoelectric switch suitable for higher nominal currents must be extremely sturdy, with it individual components having a relatively high weight. However, the necessity of moving large electrode weights makes achieving a sufficient speed of the thermoelectric drive difficult.